This invention relates to electronic circuit packs and shelf and electronic circuit pack combinations.
In the electronics industry, electrical equipment includes shelves which receive circuit packs into shelf receiving stations in which the circuit packs are in electronically operational positions. Conventionally, means are included in each pack to secure the pack in its operational position and which also allows for pack removal from its receiving station. In each pack, this securing means is normally in the form of two latches which are pivoted at opposite end parts of a face plate at the front end region of the pack. The latches operate against abutment surfaces of the shelf with a levering motion to move into latching positions while urging the circuit pack along a small and final stage of movement into its operational position. In this position, electronic circuitry of the pack is electrically connected into a back or mid plane at the rear of the shelf. Each latch has an operating lever to enable latch movement into and out of its latching position. The operating lever needs to be accessible from the front of the shelf for manual operation.
For safety reasons and to prevent equipment damage, it is an industry requirement that each shelf shall have a frontal plane, as specified in Bellcore GR-63-CORE and ETSI 300-119-2, beyond which a circuit pack must not project when in its operational position. This requirement hence places a restriction on the size of each circuit pack which may be received in a receiving station, thereby restricting the space available for the electronic circuitry of the pack. Thus, the surface area of a substrate, e.g. a printed circuit board, is limited with attendant restrictions upon the placement and availability of location spaces for conductor lines and electrical components of the electronic circuitry carried upon the substrate. In order to maximize the potential surface area available for electronic circuitry of a circuit pack to be disposed within a shelf, the latches are suitably designed so that, in their latching positions, their operating levers tend to lie towards vertical positions when the circuit pack is in its operational position within the shelf. In this position, the operating levers lie at, or behind but close to, the frontal plane of the shelf. To enable the levers to be manually accessible for pivoting the levers out of their latching positions, the faceplate and the electronic circuitry are placed rearwardly of the vertical locations of the operating levers.
The present invention seeks to provide an electronic circuit pack and a shelf and electronic circuit pack combination which is constructionally different while enabling greater scope for circuitry design.
Accordingly, the present invention provides an electronic circuit pack comprising a substrate carrying electronic circuitry and a faceplate mounted to a front region of the substrate, and the faceplate having a front wall extending along and forwardly of the front region of the substrate and the front wall having; i) two end parts provided at end regions of the faceplate, each end region carrying means for securing the circuit pack into a shelf; and ii) an intermediate part extending between the two end parts and disposed forwardly of the two end parts; a portion of the electronic circuitry directly behind the intermediate part of the front wall projecting forwardly of the two end parts of the front wall towards the intermediate part.
With the above circuit pack according to the invention, as with conventional packs, the position of the securing means and end regions of the faceplate are controlled by shelf size and geometry. The invention is, however, based upon the novel concept that the whole of the front wall of the faceplate need not necessarily be designed to be positioned at the same distance from the frontal plane of the shelf. Hence, in a practical structure, the securing means comprises latches at the end regions of the faceplate, the latches being pivotal to move into and out of latching positions for holding the circuit pack in a shelf, and the intermediate front wall part of the faceplate extends forwardly between the latches. The intermediate front wall part is disposed preferably in at least the forward position of the operating levers when the latches are in their locking positions. The electronic circuitry then occupies space defined behind the intermediate front wall part of the faceplate, but forwards of the end parts of the front wall.
It follows that for any particular requirement of shelf geometry and size, a circuit pack has an additional space available for its electronic circuitry behind the faceplate. This additional space may be used for increase in substrate size together with attendant space available for conductor lines and/or location of electronic components upon the substrate. Alternatively, the electronic components may extend into this additional space from the substrate without the substrate itself extending into the space. In a case where electronic components are disposed within the additional space, these components may include interface test components such as PCMCIA cards or may be memory cards which are accessible for connection to mating connectors through apertures in the faceplate.
The invention also includes a shelf and electronic circuit pack combination having a circuit pack according to the above invention fitted into a receiving station of the shelf.